Research on chinese herbal formulation

Read this interesting article about TCM herbal formulae at here

Look at figure 1 and table 2.

Facts established are:

1. About 92% of the total formulae are distributed in the range of single-herb formulae to thirteen-herb formulae. In addition, about 91% of
the total formulae (6986) are multi-herb formulae. It is also
noted that the number of multi-herb formulae having more than
17 herbs have rapidly reduced. Therefore, it is reasonable to
assume that single herbs were more commonly used as herbal
remedies for human ailments in ancient times. Later, in the long
course of adaptation and development, multi-herb formulae
were introduced by combining the pre-existing multi-herb
formulae.

2. Chinese herbal formulae with higher number of constituting
herbs were formulated by combining pre-existing formulae,
and very few entirely new formulae were developed with seven herbs or more.